Definition

1. Noun:
   • A female gamete in certain algae, fungi, and other lower plants: An oosphere is a large, non-motile egg cell that is ready for fertilization. It is specifically the female reproductive cell in organisms like some algae and fungi, which do not produce seeds or flowers.

Examples of Usage

• Noun:
  • The oosphere is fertilized by a motile antherozoid in the water.
  • In the life cycle of this alga, the oosphere develops within the oogonium.

Advanced Usage

• Botanical Context: The term is used almost exclusively in botanical and mycological texts to describe the female gamete in specific non-vascular plants and algae. It is a precise term within the study of plant reproduction.
  • The development of the oosphere precedes the formation of the oospore.

Variants and Related Words

• Oogonium (n): The structure or organ that contains and produces the oosphere.
  • The oosphere is housed within the oogonium.
• Oospore (n): The thick-walled zygote that results from the fertilization of an oosphere.
  • After fertilization, the oosphere develops into a dormant oospore.

Synonyms

• Egg cell: A more general term for a female gamete.
• Female gamete: The broad category to which an oosphere belongs.

Notes on Meaning

• The term "oosphere" is highly specialized. It is not used in the context of animals or higher plants (like flowering plants). In seed plants, the equivalent structure is typically called an egg cell or ovum within the ovule.

Noun

1. a gamete; used especially of lower plants